In general, a rubber cement prepared by dissolving a rubber composition in an organic solvent under stirring is used as the cement for adjusting a rubber product. The cement is used, for example, by coating the inner face of a tire to repair cracks or to adjust the balance of the tire. Heretofore, as the rubber composition for the above cement, rubber compositions for a cement of the room temperature curing type which are obtained by mixing a filler having a great specific gravity to a rubber and are crosslinked with sulfur or a peroxide have been used as described, for example, in Japanese Patent Application Laid-Open No. Showa 56(1981)-079134.
However, it is necessary for a cement for adjusting the balance of a tire that a filler having a great specific gravity in the powder form be mixed in a great amount so that the solid component of the cement has a great specific gravity. Due to this requirement, dispersion of components of compounding becomes difficult in the mixing stop of rubber, and the amount of the filler used for the mixing is practically limited when the dispersion and the productivity are considered.
When the specific gravity of the solid component of the cement is excessively small, it is necessary that application and drying of the cement be repeated many times to adjust the balance, and it takes great labor and a long time to adjust the tire. There is the possibility that the environment of the working deteriorates due to the increase in the amount of the organic solvent used. Moreover, in the case of the cement of the room temperature curing type, a problem arises in that crack are formed at the inside of the tire due to heat degradation during the use of the tire when the vulcanization system is not selected suitably.